Natural-color cinematography.



J. CAMPBELL.

NATURAL COLOR CINEMATOGRAPHY. Armcmon' man MAY s. w14.

Patentedsepu 10,1918.

Lsoz.

UNITED sTATEs PATENT oEEicE.

JOHN CAMPBELL, OF MIDDLESBBOUTGH, ENGLAND.

NATUBL-COLOR CINEMATQGRAPHY.

, Specification of Letters Patent.

Patented Sept. 1.0, 1918.

Application led Hay 5, 1914. Serial No. 836.502.

To al whom it may concern.'

Be it known that I, JOHN CAMPBELL, s' subject of His Majest the King of Eng- 1and,'residing at 30% ark street, Middlesbrough, in the county of York, Kingdom of England, have invented certain new and useful Improvements in Natural-Color Cinemato raphy, of which the following is a speci cation.

My invention relates to improvements in color cinematography systems in which the negative film is successively and alternately exposed through rotating color filters,.andv has for its object thesimplification of the process of obtaining correct color value negatives in four colors and the conversion of 'the black and white positives therefrom intocolor films readyI for projection, such positives after conversion carrying their own gelatin color filters as part of the film, and thus being rendered capable of vbein projected in ordinary projectors use for ordinary black and white films.

Referring first "to negatives, it has been roposed `in the specification of British atentNo. 26,671 of 1906 to use alternately records `of single color filters with a minimum exposure viz. l green and red giving ay twocolor system the positives from which are only capable of being projected in colors by a machine speciall fitted with' two revolving single color lters quite separate from the film.' Also in the specification of my ownv British Patent No. 15,478 of 1912, I propose the use of specially selected single color filters viz. blue and orange-with lunv equal exposures also giving a .two color `sysvFurther in the specification tem, the positives therefrom being capable ofbeing projected in ordinary machines. of my British Patent No. 24:,615` of 1911, I propose to use alternate records of tri-color filters each consisting of three graduated colors representing one-half of the spectrum with unequal exposures 'ving a six `color. system, the positive there rom being only capable lof being projected in color by a machine specially `fitted withY two three-color revolving filters.

In the specification of British Patent No. 26,976 of 1912 it has in addition been prosed'to use alternating records of two ad'- jacent but separate cold colors and three adjacent but separate warm colors with un' equal exposures giving .a five color system.

Now according to my present invention I use two filters of. bi-color formed of single positive, and Fig. 5

spectrum colors, one

spectrum yellow and a spectrum red giving a four color system. A total eect or transmission in the blue and -green filter equal to 4100 to 5600, and the warm yellow red filter of 5600 to red end,\giving negatives of equal character and density.`

The single spectrum colors forming each bi-color filter' may be either separate and adjacent, superimposed, or blended.

My invention is hereinafter described with l tive picture thus carrying a bi-color gelatinv `filter.

I form the blended bi-colofr filters c ZJ Fig.v 1, by preparing two gelatin. filters one blue and one green of suitable transmission vand transparency in the v,usual manner, and superimposing them one on the otherk so that the total transmission value is as above forming the' filter a. and similarly preparing two gelatin filters one yellow and one redlof suitable transparency and transmission, and superimposing them one on vthe re 1 is a view of one form of thecold of a spectrum blue and a spectrum green and the other warm of other so that the total transmission value is ter b. Y a

Alternatively I may blend the two suitable colors by means of spraying them from suitable apparatus such as atomizers on yto a transparent film of gelatin or other suitable material, the proportion of each color being .everned so as to give, in the aggregate in equal to that given above, forming the file finished filter, the effect of a transmission value as given. The correct proportion of each 'color may be easily and conveniently applied by regulation of the atomizers as to size, strength of blast, and length 'of time in action., I ma use two atomizers consecutively or sim taneously as convenient.

Or, I may dissolve the colors in suitable media for example water, alcohol, and gelatin (5 to 10%) to the proper strength and blend -in `the proper proportions andA then prepare by imbibition a gelatin filter from the blended colors so as to give the effect of a total transmission value, as given. In the Screen illustrated in Fig. 2 I place the two colors separately but adjacent. In a the cold filter isformed of a suitable spectrum blue and green, the area and depth of each being so proportioned as to give a transmission inits total effect of that previously given and in b I similarly use a yellow and red giving a transmission of a total eiect of that previously given. By either method the transmission required is verified by any of the usual methods, the depth of color being just suiiicient to prevent white light from passing. Y

These lters of the given transmission are set in suitable holders in the usual way and fixed as shown in a shutter each occupying 90o of the circumference and separated by opaque masking portions c and d also of 90 each. The negative lm is thus equally exposed alternately to blue and green and yellow and red of the given transmissions and `negatives of equal character are obtained with equal exposures.

The shutter is set and geared so as to.make one revolution for every two negatives taken, each two color filter a, a and b, b screening a successive negative and the opaque portions c, c and d d masking the-change of negative area. 4By this'invention I therefore obtain negatives of equal color value, viz. a two color negative of blue and green and a two color negative of yellow and red, under equal exposures which allows the use of the ordinary film movement.

From the negative I print and develop a positive in the ordinary way and convert the black and white positive into a ositive base carrying bi-color filters of two lended the spectrum colors which differ from'those used 1n the camera, in that they have more blue and less yellow in their transmissions and are so balanced in color that the total light effect from the cold filter is complementary to total light effect from` the warm lter. Accordlng to my invention these filters form part of the actual film and consists of the gelatin surface of each picture, converted into a bi-color screen and I find in practice that the total eiect of a transmission of i300 to 5500'in the blue and filter and a transmission of 5900 to-7100 in the yellow and red lter will give complementary condltions.

In the case of the positives I first dissolve each color in a suitable media like water and alcohol -to the proper depth of color and then dissolve a little gelatin in the solution. From 5 to 10 per cent. of gelatin gives good results. These colors are then' superimpod on the gelatin surface of the film which by imbibition and adhesion take up the color and are thus converted into color filters.

The positive films therefore carry their own gelatin color lters.

By a preferred method I first color the alternate pictures e shown in Fig. 3 and .which are printed from the negative pic\ p screen with a yellow color of suitable transmission, and depth as shown in Fig. 3, and when dry I superimpose over the yellow, a red of suitable transmission and.- depth as in Fig. 4. The total transmission in both cases is that previously stated, and verified by any of the usual methods. This finished picture film may novil be projected in an ordinary machine without the vuse of revolving or stationary color screens attached to the projector. l

The film may be colored in the manner indicated either by handor machine by means of a brush or brushes charged with the color, and moving across the film or by Aatomizers or nebulizers used eitherconsecutively or simultaneously` or by successive treatment in color baths through stencils the alternate pictures being suitably protected by parts of the stencils while the exposed ones are being treated. Y

Alternatively I may blend the two colors inthe proper proportions before applying themto the film, making the formation of the gelatin color filter by the use of brushes, nebulizers or stencils a single operation as shown in Fig. 5.

I thus convert each developed black and White positive base gelatin picture into a gelatin color filter of two colors, while still retaining the original black and white image, vand when a succession of such pictures are run through an ordinary projector in proper sequence with suicient speed, pictachment of color screens, stationary or revolving, to the projector, which approximate very closely to the natural tints.

Though I have described my invention with reference to blue, green, yellow and l and produced-from negatives taken respec- V.tures in colors are obtained without the atthereon a plurality of `tively through loi-colored filters, each of and produced from negativestaken, respectively, throughbi-colored filters, each of which is composed of two colors which,

blended, form one composite color, each Apositive icture carrying its own gelatin bicolored lter, as p rt of thefilm, said bicolored filters of lhe positive film being composed respectiv ly of two cold colors equaling single spectrum colors and two warm colors equaling singlel spectrum colors, said colors of each bi-colored filterof the positive film being blended so as to form' onecomposite color in each case, the cold colors and warm colors being so balanced ythat the total light effect from the cold color filter is complementary to the total light effect from the warm color I filter. 3. A cinematograph positive film, having pieturebeingrecorde from a negativeobtamed throu h a bi-colored filter section and colored y a composite color formed .by the superimposition on the positive film i of the two'indivldual colors ofthe bi-color filter.

ositive pictures, each 4. Av cinematograph positive film bearing thereon a 'plurality of positive pictures, each picture being recorded from a negative obtained through a bi-color filter section and vcolored by a composite color formedl by the superimposition on the positive film of the two individual colors of the bi-colored section, said bi-colors being composed respectively of two cold colors equaling single spectrum colors and two warm colors equalingv single spectrum colors, said colors being blended so as to form one composite co or.

5. A cinematograph'positive film bearing a plurality ofpositive pictures thereon, eac

picture .being'colored by superimposition by a composite color having as its' components the individual colors of a bi-color filter section through which the corresponding negative ,was recorded and retaining the color values of the original black and white corre-v sponding negative unimpaired, said bi-colors being composed respectively of two cold colors equaling single spectrum colors a'nd .two warm colors equaling single spectrum colors, said colors being blended so as to form one composite color, the cold colors and the warm colors .being so balanced that the total light effect from the cold color filter is complementary to the total light effect from the warm color filter.

In testimony whereof I have signed thisspecification in the presence of two subscribing witnesses.

JOHN CAMPBELL.

' Witnesses: l I

' J. S. WITHERS,

C. S. WITHERS,

siv 

